1. Field of the Invention
The present invention relates to a filter fan with a quick fixing device.
2. Description of the Related Art
Filter fans which are placed in a corresponding opening in a casing wall, for example of a switch cupboard, serve for the ventilation of switch cupboards, electronic control devices and computers. The filter fans have a blast in order to feed ambient air into the casing, wherein the casing is additionally provided with air exit slits. In order to avoid a contamination of the electronic devices in the casing, the filter fan has a filtering device, for example in form of a replaceable filter mat.
Such a filter fan is known from the EP 0 439 667 B1, wherein the filter fan has a basic casing with a frame. Quick fixing devices in form of spring-elastic brackets are configured on the frame in order to place the filter fan without additional screws or other mounting means without any tool into a casing opening and to be able to let it catch there by means of the spring-elastic brackets.
Furthermore, according to the DE 20 2006 009 355.9, a filter fan with a basic casing with a frame is known, wherein the frame is provided with quick coupling devices in form of spring-elastic, preferably wing-type brackets. The frame is configured continuously closed all around its periphery, wherein the brackets are molded on the frame. For this filter fan, the quick fixing devices in form of spring-elastic brackets are not cut out from a section of a side wall or of a frame of the basic casing of the filter fan but are molded on the outside on this frame or on the side walls. The filter fan or its basic casing is made of an injection molded part made of plastics so that during the manufacturing of the frame the additional brackets are already molded in one piece with the frame thereon or can be configured in one piece. This being, the brackets are placed practically on the outside on the frame and are orientated outwards for example in a cutout in a mounting wall when the filter fan is mounted. Moreover, the frame is configured continuous throughout, this being seen around the periphery of the filter fan, for example as a single component. Due to the additional molding of spring-elastic brackets on the frame of the filter fan, there are no openings any longer in lateral outer walls and the frame is configured substantially closed throughout around the periphery of the filter fan. Thus, the penetration of unfiltered air, for example into a computer casing, is efficiently avoided. No water can penetrate through the side walls into the inside of the filter either and thus a filter mat cannot suck itself full with moisture.
This being the case, it must however be considered disadvantageous that in the lacquered sheet metal cutouts of a mounting wall an insufficient catching of the brackets is achieved in the edge area of the sheet metal cutouts which is due to the fact that the peripheral edge of the sheet metal cutout does not have the configuration of sharp edges which is necessary for a perfect catching. Due to the coat of lacquer on the sheet metal of the switch cupboard, among others also in the edge or border area of the sheet metal cutouts, no sharp edges are necessary for a perfect catching so that the roundings created by the coat of lacquer in the edge area do not guarantee any sufficient support of the brackets in the edge or border areas of sheet metal cutouts. Add to this that for this filter fan the whole corner of the quick fixing device is cramped on an oblique contour so that the matter is here not of a direct catching which results in that the fit of the catching corners in lacquered sheet metal plates was insufficiently sure because of the rounded edges in the sheet metal because of the applied colour and thus because of the missing sharp edges and that it could thus come to an autonomous disengagement of the filter fan from its support in the sheet metal cutout of the switch cupboard.
It is apparent that the filter fan can be additionally equipped in a way known in itself with a filter mat and/or a blast and/or air conduction devices or the like. Of course lamellae which serve as air conduction device can also be configured swivellingly moving. It is basically possible to place only one single or preferably several spring-elastic brackets on the frame, as described hereunder.